As is well-understood in the art, a lithographic process includes the patterned exposure of a resist so that portions of the resist can be selectively removed to expose underlying areas for selective processing such as by etching, material deposition, implantation and the like. Traditional lithographic processes utilize electromagnetic energy in the form of ultraviolet light for selective exposure of the resist. As an alternative to electromagnetic energy (including x-rays), charged particle beams have been used for high resolution lithographic resist exposure. In particular, electron beams have been used since the low mass of electrons allows relatively accurate control of an electron beam at relatively low power and relatively high speed.
In reflective electron beam lithography, a lenslet of a mirror made by micro-electro-mechanical systems (MEMS) is used to reflect electrons back to a wafer for patterning. Typical lenslet structures include insulators between metal electrodes that are hit by electrons, which causes charging and deteriorates lenslet functionality. Accordingly, improved devices and methods are needed.